Method of improving olefinic gasoline blending components



United States Patent METHOD on IMPRGVING OLEFINIC GASOLINE BLENDING COMPONENTS Weldon G. Annable, Robert M. Haines, and William L. Jacobs, Crystal Lake, 11]., assigno'rs to The Pure Oil Company, Chicago, 111., a corporation of Ohio No Drawing. Filed Nov. 211, 1958, Ser. Nb. 775,715 '10 Claims. cl. 208-144) reduced to" the lowest level possible without afiectin'g'the' leaded research octane number of the products. The invention is directed to a specific hydrogenation treatment and to conditions found to be applicable to particular selected fractions of catalytically cracked gasolines.

Modern automotive engines have required fuels of increasingly high anti-"knockquality, and thepetroleum industry has responded by adopting a number of specialized processes for upgrading the octane number of gasoline blending components. One of the most widely employed present-day processes is catalytic cracking, in which paraffinic petroleum fractions are broken down into lighter olefinic and parafiinic hydrocarbons. Another widely used process is polymerization, wherein light olefinic molecules combine to form heavier olefinic molecules boiling within the gasoline boiling range. In the products of both of these types of processes, the higher octane numbers are contributed by the olefinic constituents.

While these olefin-containing" gasoline blending components possess high octane ratings, they aresensitive; that is, the numerical difierence" between theresearch method octane number and the motor method'octane number is high. These high sen'sitivitie'sa're reflected in unsatisfactory fuel performance in the more recently de} veloped engines. It is one of the features of this invention to provide a means for reducing the sensitivities of' these fuels without deleteriously aftectingresearch-method and road-octane ratings. In essence, the motor' method' octane number is raised Without reducing the .researchmethod octane rating.

' When the olefin-containing, catalytically cracked", and

polymeric gasolines are used in modern,- compact; high-' temperature engines; troubleisalso experienced in the formation of deposits within the induction systems and other parts of the engines. The'fuels are said to be dirty. It is a -sec'ond feature of this invention to provide a means for reducing the dirtines s resulting from these fuels without deleteriously' affecting the researchmethod octane rating and road performance.

In generaL-the prior arthas recognized the undesirability of the sensitivity of olefinic containing gasoline's, and has been partially successful in overcoming; it by anumber of similar means. For example, the blendingcharacte'n istics of olefins andparafiins are suchthat theolefin content of ablend' containing both can be reduced to about 50%, by com'positin'g the" olefin-containing constituent With-a'parafliiiiccon'stitu'ent, without markedly decreasing the research octane rating; The motor-method octane rating is increased, thereby decreasing sensitivity. An analogous result can be achieved by completely saturating, by hydrogenation, a portion of the full-boiling-range material, and recombining the hydrogenated portion with the'remaining olefin-containing portion in a ratio such that the total olefin content of the recombined material is only about v. It is apparentthat both methods consist essentially of blending olefinic and parafiinic ma terials. While these methods have been successful in reducing sensitivity, they have had little or no effect on the dirtiness caused by the final composition.

In accordance with this invention, it has been found that both the sensitivity and dirtiness can be markedly decreased, without delteriously alfecting research octane number or road performance, by partially hydrogenating the olefinic constituents of cracked and polymeric gasolines to reduce the olefin content to about 30-75% v., depending on the original olefin content. The maximum extent of saturation possible is also dependent on the characteristics of the particular material being treated.

By employing the instant process, reduced sensitivity is achieved as with the prior art methods described above, i.e., a balanced ratio between low sensitivity with low-octane paraffinic constituents-and high sensitivity with high-octane olefinic constituents is achieved. But in addition to this, the" instant process simultaneously achieves increased cleanliness, which has not been possible by prior art methods. It becomes a primary object of this invention to provide a method whereby the sensitivity and dirtiness of olefin-containing gasoline blending components are significantly reduced by hydrotreating the olefin-containing material at conditions such that the olefin content ofthe material is reduced to the greatest extent possible" without deleferiously affecting" research octane number. v a T Anotheriobject of the invention is as provide zi -reces for improving the quality of olefinic gasoline'by cons .,h dws n ausifiasertai itss b dfl isi int of hydrogen whereby the desired reduction of olefinic content is obtained. 7

A particular feature of this invention is the finding that, contrary tothe prior. art, the degree or extent of hydro- A genationof the olefinic constituents in an olefinic gaso line cannot be controlled by temperature regulation, pressure regulation or space velocity to accomplish the improvements sought herein, but that the degree of hydrogenation is a direct function of the amount of hydrogen present or made available for the reaction. Another feature of the invention is the discovery that this type of hydrogenation reaction must be carried out at or above a particular minimum or threshold temperature before the extent of hydrogenation becomes a function of available hydrogen, regardless of pressure, space velocity, fu1= ther increases in temperature, etc., to obtain the results as will be hereinafter described;

In order to illustrate the invention, the following examples are given:

EXAMPLE 1 A conventional cat. poly. gasoline was subjected to catalytic hydrogenation over -a catalyst consisting of 9% molybdena on alumina (Filtrol R-3241). At a temperature of 500 F., pressure of 300 p.s.i.g., liq,uid space velocity of 2.5 v./hr./v., and hydrogen rate of 2000 ftfi/bbl. of hydrocarbon charge, hydrogenationldidinot take place to any measurable extent. -On the other hand, when the temperature was raised to 625 F. while holding the other conditions constant, complete hydrogenation occurred.- When space velocity' was' increased to 9.85 v./hr./v at 625 F. and 300 p.s.ifg'., the'de'g'r'ee of hydrogenation was controllable by varying the hydrogen rate. The ing results were obtained:

follow- As can be seen, 22.2% v. of the olefinic constituents was saturated at a hydrogen rate of 465 s.c.f./bbl., reducing the sensitivity of the product by 3.2 units without substantial loss in RON. The resulting fuel was cleaner and had improved performance characteristics.

EXAMPLE 2 Light FCC gasoline, having an ASTM distillation endpoint of 160 F., and containing 49.0% v. olefinic hydocarbons, was subjected to mild hydrotreating over the catalyst used in Example 1. Partial hydrogenation was achieved at 650 F., 300 p.s.i.g., and 10 v./hr./v. by varying the hydrogen in a lower range than was effective in treating polymer gasoline. At a temperature of 625 F., substantially no hydrogenation occurred. Experimental results were as follows:

Table II Olefin Octane Numbers Content, Sen siti- H: Rate (s.c.f.lbb1.) Percent vity v MON RON (leaded) (+3 cc.) (+3 cc.)

From these data, it is apparent that reducing the olefin content of the light FCC gasoline to about 34%, reduced sensitivity by 2.2 units without substantial loss in RON. The resulting fuel showed improved cleanliness and engine performance.

EXAMPLE 3 The necessity for having an olefin content greater than about 40% in blending components to be treated in accordance with our invention was demonstrated by partially hydrogenating a full-boiling-range FCC gasoline over the catalyst used in the previous examples. It was found necessary to increase the reaction temperature to 700 F. to induce partial hydrogenation. Experimental results were as follows:

Table 111 Product H1 Rate (s.c.f.lbbl.) Olefin Octane Numbers Content, Sensiti- Percent vity V. MON RON (leaded) (+3 cc.) (+3 cc.)

1 Space velocity reduced to 5 v./hr./v.

From these data, it is apparent that a fuel of better performance cannot be prepared by our method when the 4 olefin content of the material to be treated is less than about 40% v.

In order to further illustrate the invention, a series of experiments were conducted using the same catalytic polymer gasoline and hydrogenation catalyst as in Example l, but the process conditions were varied in order ti detect the influence on the percentage of olefin saturation. The following tabulation illustrates the conditions and saturation results of these experiments.

Table IV HYDROGENATION OF OAT. POLY. GASOLINE Temp. Press. Hr Rate Satura- Run N0. F.) (p.s.i.g.) LVHSV (s.c.f./ tion bbl.) (percent) 1 Approximation.

The characteristics of the several charge stocks are given in Table V following.

Table V INSPECTION DATA ON CHARGE STOCKS Property Get. Light Full Range Poly. FOO 7D-587 FCC 7D-445 Gravity, API 64. 5 81. 2 58.3 Reid Vapor Press, p.s.l 6.5 13.9 8.0 ASTM Distillation, F.:

IBP 104 5% 185 99 113 10% 217 101 20% 241 103 131 30% 254 106 143 40% 265 110 162 50% 276 114 196 60% 286 119 238 70% 297 283 80% 309 134 322 90% 338 144 359 95% 372 382 EP--- 412 166 393 Ree 98. 0 99. 0 98.0 Res 1.2 0.6 1. 1 Loss. 0.8 0.4 0.9 Refractive Index, vi /D 1 4120 1.3780 1 4220 Vol. Percent Naphthenes and parafiins 0 50 43 Vol. percent Olefin 100 49 32 Vol. percent Aromatics..- 0 1 25 Wt. percent Sulfur 0.006 0. 017 0.025 Research Octane- +0.0 ml. TEL 97. 5 94.0 93. 4 +3.0 ml. TEL-.. 101.4 100.6 98.8 Motor Octane +0.0 rnl. TEL 82.0 83.3 80.9 +3.0 ml. TEL 86.0 89. 1 87.3 Sensitivity 3.0 ml. TEL 15.4 11. 5 11. 5

Referring to Table IV, runs 241 and 244 show that at the 550 F., 100 p.s.i.g., and 2.5 LVHSV level, even with an H -rate of near 2000 s.c.f./bbl., no reaction occurred. In runs 245 and 246, the only substantial change was pressure, and at best only 6.0% saturation resulted. Runs 247 and 248 show that under these pressure, spacevelocity and H -rate conditions, an increase in temperature to 600-605 F. brought about complete saturation. The balance of the runs, that is, 250 to 266, were at or above this threshold temperature and all were at 300 p.s.i.g. pressure. A comparison of runs 247 and 248 with run 250 shows that a drop in H -rate caused a drop in percent saturation. Comparison of runs 250 and 251 shows that an increase in H -rate increased the percent saturation, even though it was already at a 92% level.

appease .011 theotherihand, cnmparingrunsiZSl and-.252 shows that qincreasinguor :even, .doublingithe .spacemelocity had ration. zIn runl2'5 t, a further increase in-space velocity a1 and reduction in -H rrate caused alarge decrease in percent saturation. In comparing 254 and,255,at the same temperature, pressure and space. .ve1ocity,..i-t. is.s een that anincrease in H -rate again doubled the percent saturation, and in run25 6 afurther'increase in H -rate under these same conditions caused another jump in percent saturation. Runs 257, 258 and ;266. s l1ow these same effects {of H rate at the 70% saturation level. it is important that the reactionbe'conducted at a temperature of at least about 600 F. with an H -rate of more than 920 s.c.f./bbl. of feed, regardless of pressure and space velocity, in order to attain a saturation of from to 25%, or to leave an olefin content of 30% to 0.

In conducting the process of hydrogenation of olefinic gasoline blending components in accordance with this invention, it is only necessary to use a gasoline having 40% by volume or more of olefinic components and subject this gasoline to hydrogenation at a temperature of at least about 600 F., at elevated pressures, at a liquid volume hourly space velocity of at least about 2.5, and control the hydrogen rate within the limits of about 400 s.c.f./bbl. to 3000 s.c.f./bbl. to reduce the olefin content to the lowest level possible without afiecting the leaded research octane number, that is, to reduce the olefinic content to between about 30% to 75% by volume depending on the olefin content of the original feed gasoline. Where the original olefin content is about 90-100% by volume, the maximum decrease in leaded sensitivity is attained, without deleteriously affecting the research octane number and attaining the maximum appreciation in motor octane level, at an olefin content of about 70% to 80%. In the lower range of original olefin content, between above about 40% by volume up to 60% by volume, the final olefinic content should be about 32% by volume to 36% by volume to attain maximum reduction in leaded sensitivity without loss in research octane number.

These results are readily and consistently obtainable through controlling the hydrogenation reaction by limiting the amount of hydrogen available for the reaction, i.e., by limiting the volume of hydrogen per volume of feed While maintaining a threshold temperature of at least about 600 F., regardless of pressure or space velocity. This concept is contrary to customary ways of controlling hydrogenation reactions. For example, in general the art teaches that the degree of hydrogenation can be controlled by control of any one of the usual variables. It is often stated in the art that using the same catalyst at the same temperature with the same amount of hydrogen, and at through-puts of about 1.5 to 2 v./v./hr., the pressure is maintained at lower values so as to cause partial saturation of the feed hydrocarbon. The instant experiments prove that this mode of operation is not controlling, establish that space velocities are not controlling, and that a threshold temperature must be reached before the desired partial hydrogenation can be accomplished. Furthermore, the process need not be applied to special fractions of the olefinic gasoline to attain maximum benefits with respect to leaded sensitivity and octane appreciation.

In carrying out the method of this invention, the hydrogenation may be carried out batch-wise or continuously in the presence or absence of a catalyst. However, it is preferred that a catalyst be used as long as the method is capable of saturating only the more reactive olefinic components, and for this purpose any catalyst having hydrogenation activity may be used. Suitable catalysts include oxides and sulfides of group VI and VIII metals, and more specifically oxides of cobalt or molybdenum, :Raney nickel, lnickelssulfide, tungsten sulfide, imolybdenumsulfide, and, mixtures of metal sulfides ..or..oxides,.:used 'alone orconca .carrier such .as alumina, :clay,;pumice,..etc. Satisfactory :results are obtained with .a catalyst consisting.of'9.% by. wt. :ofsmolybdena-on an alumina support. The .feed. stock to "be treated is vapor- -;ized, tmixedzwith the required :amount .of hydrogen and passed .overv a=catalyst in. a :reaction. zone heated to about 600 F. or higher .if.-inecessary. The conditions of .pressure and space velocityare regulated to .values. sufiicient to allow the reaction to-beginJandatheJdegreeof hydro- .genation is :controlled .by regulation of the Zamount of hydrogen available for the reaction.

Feed stock forathe process. of this invention includes those blending components,.zboilingiwithin:the.;gaso1ine boiling range, i.e., about 100 F. to 400iiF.,cwhich.contain more than 40% by volume of olefins. Example feed stocks are polymer gasolines, the low-boiling portions of fluid-catalytic-cracked gasolines, and various fractions of these types of materials. In general, where the fraction being treated has an olefin content of %-100% by volume, the amount of hydrogen used is adjusted to reduce the olefin content about 1820%. In using an FCC gasoline where the original olefin content is 45 to 52% by volume, it is only necessary to adjust the amount of hydrogen so as to reduce the olefin content by an amount equal to about 10% to 20%.

What is claimed is:

1. The process of decreasing the sensitivity of olefinic gasoline blending stocks containing at least about 40 percent by volume of olefins which comprises subjecting said blending stocks to hydrogenation at a temperature of at least about 600 F., a pressure of at least about p.s.i.g., a liquid volume hourly space velocity of at least about 2.5 and controlling the amount of hydrogen during the reaction to between about 400 to 2000 s.c.f./bbl. as the reaction proceeds to attain the greatest increase in motor octane research number with the least decrease in research octane number.

2. The process of decreasing the sensitivity of a catalytic polymer gasoline containing at least about 40 percent by volume of olefins which comprises subjecting said catalytic polymer gasoline to hydrogenation at a tempera ture of at least about 600 F., a pressure of at least about 100 p.s.i.g., a liquid volume hourly space velocity of at least about 2.5 and controlling the amount of hydrogen during the reaction to between about 400 to 2000 s.c.f./ bbl. as the reaction proceeds to attain the greatest increase in motor octane research number with the least decrease in research octane number.

3. The process in accordance with claim 1 in which the feed blending stock is a catalytic polymer gasoline having an olefin content of about 100% by volume and about 18% to 20% by volume of said olefins are hydrogenated during said reaction.

4. The process in accordance with claim 3 in which said reaction is conducted at a temperature of about 625 F. at a pressure of about 300 p.s.i.g. using a liquid volume hourly space velocity of about 2.5 with the amount of. hydrogen regulated at 465 to 710 s.c.f./bbl.

5. The process in accordance with claim 1 in which the blending stock is an FCC gasoline having an ASTM end-point of F. and contains about 49.0 volume percent of olefins and about 10 %to 20% by volume of said olefins are hydrogenated during said reaction.

6. The process in accordance with claim 5 in which said reaction is conducted at a temperature of about 650 F. at 300 p.s.i.g. with a liquid volume hourly space velocity of about 10 and using about 300 s.c.-f./bbl. of hydrogen.

7. The method of treating an olefinic gasoline to decrease the sensitivity and tendency to form induction system deposits which comprises subjecting an olefinic gasoline containing about 100% by volume of olefinic hydrocarbons, and characterized by having an MON of about 86.0, a RON of about 101.4, and a leaded sensitivity of about 15.4, to catalytic hydrogenation in the presence of a molybdena-alumina catalyst at a temperature of at least about 600 F. using pressures of about 300 p.s.i.g. under a space velocity of about 9.85 v./hr./v. and controlling the hydrogen rate to about 465 s.c.f./bbl., continuing said reaction until the olefin content of the product is about 77.8 volume percent and recovering a product having a decreased leaded sensitivity, an increased MON and substantially the same RON.

8. The method in' accordance with claim 7 in which the olefinic gasoline is a catalytically polymerized gasoline.

9. The method in accordance with claim 7 in which the olefinic gasoline has an olefinic content of at least 40% by volume.

10. The method in accordance with claim 7 in which the temperature is maintained at about 625 F. throughout the reaction.

References Cited in the file of this patent UNITED STATES PATENTS 

1. THE PROCESS OF DECREASING THE SENSITIVITY OF OLEFINIC GASOLINE BLENDING STOCKS CONTAINING AT LEAST ABOUT 40 PERCENT BY VOLUME OF OLEFINS WHICH COMPRISES SUBJECTING SAID BLENDING STOCKS TO HYDROGENATION AT A TEMPERATURE OF AT LEAST ABOUT 600*F., A PRESSURE OF AT LEAST ABOUT 100 P.S.I.G., A LIQUID VOLUME HOURLY SPACE VELOCITY OF AT LEAST ABOUT 2.5 AND CONTROLLING THE AMOUNT OF HYDROGEN DURING THE REACTION TO BETWEEN ABOUT 400 TO 2000 S.C.F./BBL. AS THE REACTION PROCEEDS TO ATTAIN THE GREATEST INCREASE IN MOTOR OCTANE RESEARCH NUMBER WITH THE LEAST DECREASE IN RESEARCH OCTANE NUMBER. 